Abstract
It is possible for a volume of fluid to become trapped in the space between two adjoining teeth as the tips of the teeth engage in Gear Pump with involute teeth. This trapped fluid leads to several harmful results, for example fluctuating pressure and aeration of pump. In this study, hence, theoretical and experimental analyses on this'Trapping'were accomplished as using relief port(or escape port), one of the means for avoid it. Also, the grasp and analysis on variational type of the internal pressure in parallel with above experiments are achieved so that hydrodynamic behaviors in pump were contemplated.